Giardia are parasitic protozoans, or single-celled organisms, that cling to the surface or float in the mucus lining of the intestines of mammals, including dogs and humans. It is the most commonly identified intestinal parasite in North America and can be found worldwide.
The parasite is transmitted through fecal matter. Once in the motile feeding stage, it develops into a cyst while traveling through the large intestine. Once outside the host, the cyst can survive in a moist environment for up to several months. Because the cyst requires a moist or even wet environment, the most common way for an animal or human to ingest Giardia is through contaminated water. Streams, lakes, swimming pools, hot tubs, rivers, and wells can all harbor the organism, although contaminated food can also cause the infection.
The infection, known as Giardiasis or ‘beaver fever’, causes diarrhea, abdominal cramping, gas, bloating, frequent pale and loose mucous stools, nausea, weight loss, and overall listlessness. The gestation period for the infection is 7 to 10 days, and symptoms commonly last between three and twenty-five days, with severe cases potentially lasting months.
Diagnosing Giardia
For diagnosis, a stool sample is required, although this is not always conclusive if no cysts are present. Several samples may be needed, depending on the severity of the infection, as cysts are only passed periodically. Treatment typically involves one of two antiprotozoal medications, and dogs dehydrated from severe diarrhea and nausea may require I.V. fluids and hospitalization. If cysts are found in your pet’s stool, they should be treated even if they are symptom-free and show no clinical signs.
In healthy adult dogs, Giardia symptoms are usually mild, and recovery is quick with treatment. In puppies, elderly dogs, or those with weakened immune systems, however, the infection can be much more dangerous and requires serious treatment.
Recently, a Giardia vaccine has been licensed in North America, and studies have shown it to be effective in some cases, though not all. Ask your veterinarian for more information about this and other vaccines.
Preventing Giardia is difficult with dogs, as the only way to kill the cysts in contaminated water is to boil the water or filter it. Since dogs live for the moment and will not wait for water to boil or undergo filtering before drinking from a lake, stream, or swamp, the chance of them ingesting cysts is far greater than it is for humans. Therefore, if you suspect your dog may have come into contact with contaminated water 7 to 10 days ago and they are beginning to show symptoms, take them to the vet immediately. Early treatment helps limit the impact of the infection on both your pet and your pocketbook!
